The present invention relates to turbines having circumferentially-spaced buckets about a rotor wheel and particularly relates to a bucket damper assembly including a pin disposed between adjacent buckets for damping bucket vibration.
As well known, turbines generally include a rotor, for example, comprised of a plurality of rotor wheels, each of which mounts a plurality of circumferentially-spaced buckets. The buckets typically include an airfoil, a platform, a shank and a dovetail, the dovetail being received in a slot or opening in the turbine wheel for securing the bucket to the wheel. The airfoils, of course, project into the gas path, e.g., the hot gas path of a gas turbine, and convert kinetic energy of the gases into rotational mechanical energy. During engine operation, vibrations are introduced into the turbine buckets and, if not dissipated, may cause premature failure of the buckets.
Many different forms of vibration dampers have been proposed and constructed to minimize or eliminate vibratory action of the buckets. For example, see U.S. Pat. Nos. 6,354,803; 5,156,528; 6,390,775; 6,478,544; 5,827,047; and 6,450,769. While the vibration dampers disclosed in these patents may be useful to damp vibrations in certain types of turbine, they do not appear to be completely applicable to or effective with respect to buckets having a short shank and shroudless airfoil tips. It is therefore desirable to provide a damper assembly including a pin specifically useful for this type of turbine bucket, although the assembly and pin have applicability to other turbine buckets.